Longtime keeps several clocks — yours, your Space's, each person's, each connection's and each occasion's. Here is what each one decides, and how they fit together.

Longtime keeps each time in the clock it belongs to. A connection keeps the timezone it happened in, an occasion follows the place it was in, and each person has their own. Your Space's timezone fills in whenever nothing more specific is known, and your own timezone only decides how the dates Longtime works out for you are shown.

So changing a timezone never moves anything you have already logged. A dinner at 8 pm stays at 8 pm.

Yours

Set in your profile. It starts as your device's timezone when you sign up.

It decides how Longtime shows you the dates it works out itself: when you were last in touch with someone, when a note was left, when a snoozed suggestion comes back. It does not change the time shown on a connection — that is the connection's own.

Your Space's

Chosen when you make the Space, and changed in the Space's settings. A new Space starts with your own timezone.

It is the Space's home clock:

the interview reads the times you tell it in this timezone — "Friday at 7" is 7 in the Space's timezone;
it decides when a day starts for the Space, such as when a birthday is today;
a search by date — "since June 1st" — reads the date in it;
anyone without a timezone of their own follows it.

A person's

Set when you edit their details, or brought in from a contact card in an import. Until you set one, they follow the Space's.

Their page shows what time it is for them. In a birthday calendar, their birthday is an all-day event on the date itself.

A connection's

A connection keeps the timezone it was logged in: the Space's when you tell the interview, or the event's own when it comes from a calendar. Its time always reads as it was there — a call at 9 am in Lisbon says 9 am wherever you are when you look at it.

To log one in another timezone, correct its time with the pencil in the interview; the correction has a timezone field. Editing a connection later changes its times, not its timezone.

An occasion's

Chosen when you make the occasion. It starts as your device's timezone; set it to the local one for a trip abroad.

It places the occasion's days on your timeline, and it decides which notes on a person's page sit inside the occasion in their history. It does not decide which connections are on the occasion's days — that goes by each connection's own date, where it happened.

An example: a week in Lisbon

Your Space is set to New York, and you spend a week in Lisbon.

Make an occasion, "Week in Lisbon", with its timezone set to Lisbon.
Tell the interview "dinner with Ana tonight at 8". It reads 8 pm New York time, because the interview always uses the Space's timezone, not where your phone is. Correct the time with the pencil and set the timezone to Lisbon.
The occasion's page offers the dinner, because its date in Lisbon is one of the occasion's days. Add it, and it sits inside the occasion.
Back home, the dinner still says 8 pm — the time it was at the table.